Engine 2nd Gen R56 N12 Engine Air/Fuel mixture

Discussion in '2nd Generation: 2007+ R55 through R61' started by Ron Day, Feb 24, 2019.

  1. Ron Day

    Ron Day New Member

    Feb 19, 2019
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    I've read that the A/F at idle is supposed to be somewhere around 14.6/1 but nothing else and even that I am not sure is for the N12 engine. Anybody have spec's for proper A/F at idle and under load for the N12?
     
  2. MCS02

    MCS02 Moderator
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    Jul 31, 2009
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    I can not find anything in the Bentley manual that tells what the A/F should be. Sorry I am no help
     
  3. MCS02

    MCS02 Moderator
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    From your other thread I thought you had an S not a straight Cooper. Sorry I don't know how I got you had a Cooper S.
     
  4. Ron Day

    Ron Day New Member

    Feb 19, 2019
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    Turns out you don't need Mini specific numbers for this one:

    From Wiki: "Any mixture greater than 14.7:1 is considered a lean mixture; any less than 14.7:1 is a rich mixture – given perfect (ideal) "test" fuel (gasoline consisting of solely n-heptane and iso-octane). In reality, most fuels consist of a combination of heptane, octane, a handful of other alkanes, plus additives including detergents, and possibly oxygenators such as MTBE (methyl tert-butyl ether) or ethanol/methanol. These compounds all alter the stoichiometric ratio, with most of the additives pushing the ratio downward (oxygenators bring extra oxygen to the combustion event in liquid form that is released at time of combustions; for MTBE-laden fuel, a stoichiometric ratio can be as low as 14.1:1). Vehicles that use an oxygen sensor or other feedback loop to control fuel to air ratio (lambda control), compensate automatically for this change in the fuel's stoichiometric rate by measuring the exhaust gas composition and controlling fuel volume. "

    So..... This raises another interesting question. I have a 2187 error (lean air fuel mixture bank 1 ) but when I dial in my Scan Gauge to measure Air/Fuel it get 14.6? and when driving it drops down to 12.8 - 13 on acceleration. On deceleration it goes WAY up, but that makes sense when no fuel is being put into the system.
     
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  5. Dave.0

    Dave.0 Helix & RMW Powered
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    You have a bad O2 sensor, 1st sensor. Try the dealership to see if it is still covere7under the emissions warranty 10 years 100,000 miles. If not covered buy a new OEM O2 and replace it.
     
  6. Sully

    Sully Administrator
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    Hmm.. this is something I didn’t know. The deal has a 100k or 10yr emission warranty? Was that an additional option or did all MINIs come with this?
     
  7. Sully

    Sully Administrator
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    Just looked it up, in my manual it’s pages 35-37.. and it’s 8yr or 80k miles. Not sure mine would still be covered based on the modifications.. but that’s interesting for sure.
     
  8. Dave.0

    Dave.0 Helix & RMW Powered
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    It was extended as part of a recall or something. I am way past it but they did replace one O2 on my RMW header one time. It all depends on who you know at the dealership. :rolleyes:
     
  9. Ron Day

    Ron Day New Member

    Feb 19, 2019
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    02 sensor appears to be good based in voltage and error codes. I am third owner and this is an 09, scared to go to dealer bad experiences with previous 2010 clubman.
     

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